This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The filter bank is a fundamental component of MPEG audio standard applications. Specifically, a filter bank is used for the time/frequency transformation of the time-domain audio signal. Accordingly, in typical audio coding applications, filter banks are frequently used to divide input signals into subband frequencies (subbands). The subbands are then modified using specific techniques to obtain a desired output signal. In some coding applications, a higher frequency resolution is required than can be obtained from using a single filter bank. In this case, subband frequencies may be further divided into smaller subbands using one or more additional filter banks. Such systems are often referred to as cascading filter bank systems.
Subband-domain filtering operations are also used in typical audio coding applications. Subband-domain filtering may include infinite impulse response (IIR) and finite impulse response (FIR) operations. In a cascading filter bank system, the number of operations required to carry out filtering operations in the subband-domain increases in complexity with every additional filter bank employed. This complexity results in an undesirable and computationally expensive process. Thus, a method and system is needed that reduces the complexity of carrying out subband-domain filtering in a cascading filter bank system.